Reactive Power Control Lecture Notes

Lecturer: Chinmay Deshpande

Introduction

• Topic: Reactive Power Control
• Subtopic: Necessity of Reactive Power

Analogies of Reactive Power

1. Water Tower Tank Analogy

   • Procedure: Climbing up a ladder with a bucket of water, dumping it, and returning.
   • Explanation: Up and down movement without a load is like reactive power (no work done).
   • Active Power: Flow of water from source to load.
   • Reactive Power: Return from tank to source.

2. Beer Foam Analogy

   • Analogy: Foam is useless but takes space.
   • Apparent Power: Full glass of beer (total).
   • Real Power: Drinkable portion of beer.
   • Reactive Power: Useless foam.
   • Power Factor: Ratio of real power to apparent power.

3. Packet of Wafers Analogy

   • Actual Wafers: Real power.
   • Air and Preservatives: Reactive power (necessary but not useful).
   • Total Packet: Apparent power.

Definitions of Reactive Power

• Active Power: Contributes to energy consumed or transmitted.
• Reactive Power (VAR): Does not contribute to energy but is essential to maintain voltage levels.
  • Reason: Maintains voltage for active power delivery through transmission lines.
• Importance: Ensures sufficient reactive power to prevent voltage sag and maintain system operation.
• Essential: Moves active power towards consumers and stabilizes voltage levels.
• Energy Storage Components: Inductors and capacitors.
  • Capacitors: Provide positive VAR (reactive power).
  • Inductors: Provide negative VAR.

Reactance in Electrical Components

• Inductor: Coil of wire (e.g., motors).
• Capacitor: Parallel conductive plates.
  • Operation: Exchange energy without absorbing real power.
• Reactive Power Generation:
  • Method: Use capacitors at motor locations to provide needed VAR.

Necessity of Reactive Power

• Voltage Control: Ensures proper operation of electrical equipment.
  • Permissible Voltage Range: ±5% variation.
  • Low Voltage Issues: Poor performance, light bulbs dim, motors overheat, equipment damage.
  • High Voltage Issues: Damage and shortened equipment life.
  • Optimal Range: Voltage should not deviate too much from designed range.
• Voltage Relationship: Reactive power increase leads to voltage rise; decrease leads to voltage fall.

Effects of Voltage Sag

• Reactive Power Maintenance: Essential to sustain voltage and deliver active power.
• Voltage Collapse: Insufficient reactive power leads to voltage sag and transmission failure.
  • Consequences: Cascading failures, generators disconnecting to protect themselves, system disruptions.

Reactive Power and Load

• Power Formula: Active Power P = VI cos φ
• Adjustment: Lower voltage requires higher current to maintain power.
  • Result: Increased system losses (I²R).
• Effects of High Current: System overheating, voltage drops, and potential cascading failures.
  • Protective Actions: Automatic generator disconnects to prevent damage.

Conclusion

• Summary: Importance of maintaining reactive power to stabilize voltage and ensure reliable power delivery.

End of Lecture